Cylindrical battery cell packaging and cooling configuration

ABSTRACT

Systems and methods that provide improved cooling for batteries are disclosed. A battery system according to the present disclosure may include a cooling plate, one or more battery cells coupled to one surface of the cooling plate, and one or more battery cells coupled to the opposite surface of the cooling plate. The cooling plate and corresponding batteries may be included in a battery module, and multiple battery modules electrically connected may make up a battery pack. The cooling plates may comprise channels for cooling fluid, which may be provided to the plates in parallel from a cooling fluid source. Cooling the battery cells at the ends of the cells, where they are coupled to the cooling plate, may advantageously provide one or more of improved energy density, thermal management, and safety.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/115,156 filed Aug. 28, 2018, which issued as U.S. Pat. No.10,886,580, the disclosure of which is hereby incorporated by referenceherein in its entirety.

BACKGROUND

Current electric vehicle platforms typically package a large number ofbattery cells into modules. The battery cells generate heat andtypically require cooling to maintain the cells' safe operation andlongevity. It is known in the art to run cooling tubes betweencylindrical battery cells within a module such that the tubes cool aportion of the sides of the cells. In this configuration, the coolingtubes take up space within the module and limit how tightly the cellscan be packed within the module, thereby limiting energy density. Itwould be advantageous to provide an improved cooling configuration forbattery cells.

SUMMARY

Systems and methods are disclosed herein that provide improved coolingfor batteries. The batteries of the present disclosure may provide oneor more of improved energy density, thermal management, and safety. Abattery system according to the present disclosure may include a coolingplate having a first cooling surface and a second opposite coolingsurface. The battery system may also include two or more battery cells,where each battery cell comprises a first end, a second end, and alongitudinal axis passing through the first end and second end. Thefirst end of a first battery cell is coupled to the first surface of thecooling plate and the first end of a second battery cell is coupled tothe second surface of the cooling plate, where the first battery celland the second battery cell are oriented in opposite directions. In someembodiments, the first ends of the first battery cell and the secondbattery cell may be coupled to the cooling plate with a respectivecoupling element (e.g., an adhesive).

In some embodiments, the cooling plate may have an input port and anoutput port, where cooling fluid may enter and exit the cooling plate,respectively. The cooling plate may be a generally rectangular shapehaving four edges, and the input and output ports may be located near anedge of the rectangular shape. The cooling plate may have a plurality ofcooling channels through which the cooling fluid can pass through fromthe input port to the output port. In some embodiments, the batterysystem may have an additional cooling plate configured to cooladditional battery cells, where the cooling plates are coupled inparallel to a source of cooling fluid.

In some embodiments, the first battery cell and the second battery cellmay each be a cylindrical shape. The first ends of the first and secondbattery cells may each comprise a negative face and the second ends ofthe first and second battery cells may each comprise a positive face.

In some embodiments, the first and second battery cells may each becoupled to a respective positive electrical connector at the centerportions of the second ends of the cells. The cells may each be coupledto a respective negative electrical connector at the rim portions of thesecond ends of the cells.

In some embodiments, the second ends of the first and second batterycells may each have a vent configured to release gas during a thermalevent, for example, in the case of cell overcharging or failure.

In some embodiments, the battery system may include multiple firstbattery cells that are coupled to the first surface of the cooling plateand multiple second battery cells that are coupled to the second surfaceof the cooling plate. The battery cells on each side of the coolingplate may be arranged in a plurality of rows, where each row may beoffset from an adjacent row to, for example, increase packing density ofthe cells.

In some embodiments, the first battery cells may be electricallyconnected in parallel and the second battery cells may be electricallyconnected in parallel.

In some embodiments, the first battery cells may have subgroups, wherethe battery cells within each subgroup are electrically connected inparallel, and where the subgroups are electrically connected in series.Similarly, the second battery cells may have subgroups, where thebattery cells within each subgroup are electrically connected inparallel, and where the subgroups are electrically connected in series.

In some embodiments, the longitudinal axes of the first and secondbattery cells may be parallel, and the first end of the first batterycell may be spaced apart from the first end of the second battery cell adistance less than 8 millimeters in a direction parallel to thelongitudinal axes of the first and second battery cells.

In some embodiments, the battery system may have a plurality of batterymodules, where each of the plurality of battery modules may include acooling plate, a first battery cell, and a second battery cell, andwhere the plurality of battery modules may be electrically connected inseries or parallel to form a battery pack.

In some embodiments, the first battery cell and the second battery cellmay each have a thermal conductivity that is greater in the longitudinaldirection than in a direction perpendicular to the longitudinaldirection.

In some embodiments, a method of manufacturing a battery system is usedto provide improved cooling for batteries. The method may includeproviding a cooling plate having a first cooling surface and a secondopposite cooling surface, as well as providing two or more batterycells, where each battery cell comprises a first end, a second end, anda longitudinal axis passing through the first end and second end. Themethod may further include coupling the first end of the first batterycell to the first surface of the cooling plate and the first end of thesecond battery cell to the second surface of the cooling plate, wherethe first and second battery cells are oriented in opposite directions.

In some embodiments, a method of operating a battery system providesimproved cooling. The method may include supplying cooling fluid to theinput port of the cooling plate. The method may further includeabsorbing heat, in the cooling fluid, from the ends of battery cells oneach side of the cooling plate, thereby generating heated cooling fluidin the cooling plate. The method may further include discharging theheated cooling fluid through the output port of the cooling plate,thereby removing heat generated from the battery cells.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure, in accordance with one or more variousembodiments, is described in detail with reference to the followingfigures. The drawings are provided for purposes of illustration only andmerely depict typical or example embodiments. These drawings areprovided to facilitate an understanding of the concepts disclosed hereinand shall not be considered limiting of the breadth, scope, orapplicability of these concepts. It should be noted that for clarity andease of illustration these drawings are not necessarily made to scale.

FIG. 1 shows a first battery cell and a second battery cell coupled to acooling plate in a cooling configuration in accordance with someembodiments of the present disclosure;

FIG. 2 shows a battery cell coupled to a positive electrical connectorand a negative electrical connector in accordance with some embodimentsof the present disclosure;

FIG. 3 shows an illustrative battery cell configuration with twosubgroups of battery cells in accordance with some embodiments of thepresent disclosure;

FIG. 4 shows a top view of an arrangement of battery cells on a coolingplate in accordance with some embodiments of the present disclosure;

FIG. 5 shows a cross-sectional view through the center of anillustrative cooling plate in accordance with some embodiments of thepresent disclosure;

FIG. 6 shows an illustrative configuration of battery modules inaccordance with some embodiments of the present disclosure;

FIG. 7 is a flowchart of a method for operating a battery system inaccordance with some embodiments of the present disclosure; and

FIG. 8 is a flowchart of a method for manufacturing a battery system toincrease volumetric efficiency for cooling in accordance with someembodiments of the present disclosure.

DETAILED DESCRIPTION

Systems and methods are disclosed herein that provide improved coolingfor batteries. In the present disclosure, battery cells are coupled atthe ends of the cells to opposite sides of a cooling plate. There may beone or more battery cells on each side of the cooling plate. Whenmultiple battery cells are used on each side, they may be arranged inrows that are offset from each other to increase packing density (e.g.,in a hexagonal close packed arrangement). Each battery cell may have avent on the end not coupled to the cooling plate that is configured torelease gas during a thermal event, such as cell overcharging orfailure. The battery cells may each have one end corresponding to apositive face and one end corresponding to a negative face of the cell.There may also be positive and negative electrical connectors coupled tocenter and rim portions of the battery cells at one end to enable easierconnections to busbars. Groups of battery cells may be electricallyconnected in series or parallel; in some cases, one subgroup of batterycells connected in parallel may be connected to another subgroup ofbattery cells in series.

The cooling plate in the present disclosure may have good thermalcoupling but be electrically isolated and non-conductive. The coolingplate may contain a cooling fluid such as ethylene glycol and watersolution, propylene glycol and water solution, methanol solution, etc.The cooling plate may be a generally rectangular shape, with an inputport for the cooling fluid to enter the cooling plate and an output portfor the cooling fluid to exit the cooling plate. Multiple batterymodules that each comprise a cooling plate and battery cells may becoupled in parallel to a source of cooling fluid.

FIG. 1 shows a first battery cell 102 and a second battery cell 104coupled to a cooling plate 120 in cooling configuration 100 inaccordance with some embodiments of the present disclosure. Both batterycells comprise a first end, a second end, and a longitudinal axispassing through the first and second end of the cell. In someembodiments, the battery cells may be cylindrically shaped as shown. Insome embodiments, the battery cells may be prismatic in shape (e.g.,rectangular). As shown, first end 110 of first battery cell 102 iscoupled to a first side 122 of cooling plate 120. First end 112 ofsecond battery cell 104 is coupled to a second opposite side 124 ofcooling plate 120. As arranged, first battery cell 102 and secondbattery cell 104 are oriented in opposite directions. Battery cells 102and 104 may be coupled to cooling plate 120 using any suitable couplingelement. In some embodiments, the coupling element may be an adhesive, anonconductive shroud, or both. The coupling element may provide goodthermal conductivity between battery cells 102 and 104 and cooling plate120.

First end 110 of first battery cell 102 and first end 112 of secondbattery cell 104 may each comprise a negative face of the cell. In someembodiments, the negative terminal may extend up the side of the batteryto the rim of the other end. Second ends 106 and 108 of battery cells102 and 104 may each comprise a positive face of the cell and may eachcomprise a vent configured to release gas during a thermal event, suchas cell overcharging or failure. Second ends 106 and 108 may alsoinclude a sealing gasket between the center portion and the outer rim toelectrically isolate the positive terminal from the negative terminal.In some embodiments, battery cells 102 and 104 are lithium ionbatteries. Lithium ion battery cells may comprise four sheets ofmaterial, a positive electrode sheet, a negative electrode sheet, andtwo separator sheets (e.g., microperforated plastic), rolled into aspiral. Tabs may connect the positive electrode sheet to the positiveface and the negative electrode sheet to the negative face. In someembodiments, the battery cells each comprise a thermal conductivity thatis greater in the longitudinal direction than a direction perpendicularto the longitudinal direction. For example, the spiraled sheets oflithium ion batteries typically have a greater thermal conductivity inthe longitudinal direction.

In cooling configuration 100, longitudinal axis 114 of first batterycell 102 and longitudinal axis 116 of second battery cell 104 areparallel with each other. The first and second battery cells may beoriented so that their longitudinal axes are coincident, as shown, orthey may be offset from each other. First end 110 of first battery cell102 may be spaced apart from first end 112 of second battery cell 104 adistance equal to or greater than the thickness of cooling plate 120 ina direction parallel to the longitudinal axes of the first and secondbattery cells. In some embodiments, the thickness of cooling plate 120is approximately 5 millimeters. It will be understood that this ismerely exemplary and any suitable thickness can be used. In someembodiments, the first ends of battery cells are adjacent to the sidesof cooling plate 120 or within 1, 2, or 3 millimeters of the sides ofcooling plate 120. In some embodiments, the distance between the firstends of the battery cells is less than 8 millimeters. In someembodiments, the distance between the first ends of the battery cells isapproximately 5, 6, or 7 millimeters. Accordingly, by using a coolingplate and orienting the battery cells on either side of the coolingplate in opposite orientations, the overall height of the battery systemcan be reduced or minimized. Any suitable cooling plate may be used inaccordance with the present disclosure. In some embodiments, a liquidcooled cooling plate may be used. In some embodiments, a spreadercooling plate (e.g., a heat pipe cooling plate) may be used.

FIG. 2 shows a battery cell 200 coupled to a positive electricalconnector 202 and a negative electrical connector 204 in accordance withsome embodiments of the present disclosure. These connectors may be usedon the battery cells shown in FIG. 1 . Positive electrical connector 202may be coupled to a center portion 206 of a second end 212 of batterycell 200. Negative electrical connector 204 may be coupled to a rimportion 208 of second end 212 of battery cell 200. As explained above,the rim portion of the positive face of a battery cell may beelectrically coupled to the negative face of the battery cell via theside wall of the battery cell and electrically isolated from thepositive face. Accordingly, rim portion 208 of battery cell 200 in FIG.2 is electrically coupled to first end 214 of the battery cell, whichcorresponds to the negative face of the battery cell, and iselectrically isolated from second end 212 of the battery cell, whichcorresponds to the positive face of the battery cell. The connectors maybe coupled to battery 200 using any suitable technique. For example, thecoupling may be an ultrasonic weld, a laser weld, or a fusible link(e.g., a wire bond). Having both the positive and negative connectors onthe same end of the battery cell may, for example, be advantageous insimplifying connections to the battery cell. For example, having bothconnectors on the second end of the battery cell may allow forconnections to the battery cell to be made when only the second end (andnot the first end) is accessible in a packing configuration. Theconnectors may be used to connect the battery to a load or to otherbattery cells, in parallel, series, or a combination thereof. In someembodiments, the connectors are connected to busbars, which are metallicstrips used for electrical connections.

Referring back to FIG. 1 , while only a single battery is shown on eachside of the cooling plate, it should be understood that two or morebatteries may be included on each side. The batteries on each side ofthe cooling plate may be electrically connected in series, parallel, ora combination thereof. The batteries may be connected using theconnectors shown in FIG. 2 , which may be connected to busbars. In someembodiments, the first battery cells coupled to the first side of thecooling plate may be electrically connected in parallel, and the secondbattery cells coupled to the second side of the cooling plate may beelectrically connected in parallel. In another embodiment, the batterycells on each side of the cooling plate may have subgroups, where thebattery cells within each subgroup are electrically connected inparallel, and where the subgroups are electrically connected in series.

FIG. 3 shows an illustrative battery cell configuration 300 with twosubgroups of battery cells in accordance with some embodiments of thepresent disclosure. The battery cells within the subgroups are coupledto positive and negative electrical connectors. In some embodiments, theconnectors and couplings that are used are the same as shown in FIG. 2 .The first subgroup comprises battery cells 310 and 320, which havepositive electrical connectors 312 connected to first busbar 360 andnegative electrical connectors 316 connected to second busbar 350.Accordingly, battery cells 310 and 320 are electrically connected inparallel. The second subgroup comprises battery cells 330 and 340, whichhave positive electrical connectors 332 connected to third busbar 370and negative electrical connectors 336 connected to first busbar 360.Accordingly, battery cells 330 and 340 are electrically connected inparallel. As shown, the first subgroup of battery cells 310 and 320 areelectrically connected in series with the second subgroup of batterycells 330 and 340 via busbar 360, which electrically connects thepositive terminals of the first subgroup to the negative terminals ofthe second subgroup. It should be understood that this configuration ismerely illustrative and any suitable number of battery cells may be usedin each subgroup and any suitable number of subgroups may be used. Itwill also be understood that the configuration shown in FIG. 3 may beused with battery cells coupled to one or both sides of a cooling plate.For example, the configuration of FIG. 3 may be used for battery cellson either side of the cooling plate of FIG. 1 . It will also beunderstood that while the battery cells shown in FIG. 3 are alignedalong a line, the battery cells may be arranged in multiple rows ofbattery cells (e.g., on each side of a cooling plate).

FIG. 4 shows a top view 400 of an arrangement of battery cells on acooling plate 402 in accordance with some embodiments of the presentdisclosure. As described above, the battery cells may be arranged inmultiple rows. As shown, 5 rows of battery cells are arranged on coolingplate 402. In some embodiments, the battery cells in each row are offsetfrom the battery cells in the adjacent rows. For example, as shown, afirst row 404 and a second adjacent row 406 of battery cells are offseton cooling plate 402. This can be done, for example, to increasepackaging density of the battery cells. By using a cooling plate to coolthe ends of the battery cells, the battery cells within the same row andbetween adjacent rows can be positioned relatively close to one another.This enables closer packing than using cooling tubes to cool the sidesof the cells. While only one side of the cooling plate is shown in FIG.4 , it should be understood that the same or a similar arrangement maybe used on the opposite side of the cooling plate. It will also beunderstood that the arrangement of battery cells shown in FIG. 4 can beused with cooling plate 120 of FIG. 1 .

FIG. 5 shows a cross-sectional view through the center of anillustrative cooling plate 500 in accordance with some embodiments ofthe present disclosure. In some embodiments, cooling plate 500 maycomprise a generally rectangular shape having four edges, possibly withone or more irregularities in the rectangular shape such as notch 510.In some embodiments, the cooling plate may be a different shape (e.g.,square or round) depending on the packaging of the cooling configurationand the available space for batteries. Regions 502 and 504 in thecross-section of the cooling plate may correspond, respectively, to theinput port and the output port of the cooling plate, which are not shownbut would be on the surface of the cooling plate. There may be one ormore channels in the cooling plate for the cooling fluid to travelthrough, and there may be multiple sets of input and output portscorresponding to the channels. The number of channels, channelconfiguration, and number of input and output ports may be selected withthe goal of minimizing temperature gradient across the cooling plate.For example, cross-flow channels may be selected to provide more eventemperature distribution. Cooling plate 500 comprises a channel 508configured in a “6-pass channel design.” Cooling fluid enters thecooling plate at an input port, by region 502, and travels along channel508 before reaching region 504 and exiting the cooling plate at anoutput port. The input and output ports need not necessarily beadjacent, though positioning them adjacently may be advantageous indistributing heat across the cooling plate as the cooling fluid movesthrough the channel. For example, as shown in FIG. 5 , the cooling fluidbegins traveling through the cooling plate at region 502 in a generallyclockwise manner. As the cooling fluid travels through the channel, heatis absorbed, resulting in the cooling fluid becoming more heated as itgets closer to exiting the cooling plate. As shown in FIG. 5 , arrangingthe channel such that the cooling fluid at its hottest (near region 504)is positioned near the cooling fluid at its coolest (near region 502)provides a more consistent temperature throughout the surfaces of theplate, as the temperatures balance each other out. It should beunderstood that the channel arrangement shown in FIG. 5 is merelyillustrative. In another example, there could be multiple linearchannels placed horizontally or in another configuration within thecooling plate.

The one or more channels in the cooling plate may be formed in variousways. In some embodiments, the cooling plate may be fabricated fromthree layers. The bottom and top layers may be solid layers thatcomprise the surfaces to which the battery cells are coupled, and themiddle layer may have portions removed to form the channels. In someembodiments, the plate may be fabricated from two layers. For example,there may be a thicker bottom layer, into which the channels are milledor otherwise formed, in addition to a solid top layer that is glued tothe bottom layer.

The cooling plate and batteries cells of the present disclosure may beincluded in a battery module. A battery module may comprise otherelements, such as extruded aluminum shear walls, which provide rigidityand module mounting. In some applications, multiple battery modules maybe electrically connected to form a battery pack. In some embodiments,the cooling plates of two or more battery modules may be coupled inparallel to a source of cooling fluid. This may, for example, minimizethe temperature gradient across battery modules by providing eachbattery module with cooling fluid at about the same temperature. FIG. 6shows an illustrative configuration 600 of battery modules in accordancewith some embodiments of the present disclosure. As shown, batterymodules 610 and 620 comprise respective input ports 614 and 624, outputports 616 and 626, and cooling plates 612 and 622. Cooling plates 612and 622 extend into respective battery modules 610 and 620. Coolingplates 612 and 622 may be any suitable cooling plates such as coolingplate 120 of FIG. 1 , cooling plate 402 of FIG. 4 , and cooling plate500 of FIG. 5 . One or more battery cells may be coupled to each side ofcooling plates 612 and 622 inside of the respective battery modulehousings. Cooling fluid source 602 may supply cooling fluid to inputports 614 and 624 and collect the discharged cooling fluid from outputports 616 and 626. As an example, the cooling fluid source may be a heatexchanger (e.g., a radiator) located in the front of an electric vehicleconfigured to discharge heat to the outside air. It should be understoodthat FIG. 6 is merely illustrative and that any suitable number ofbattery modules may be used.

The present disclosure includes methods of operating batteries that usecooling plates to cool the ends of battery cells. FIG. 7 is a flowchart700 of a method for operating a battery system in accordance with someembodiments of the present disclosure. In some embodiments, the batterysystem comprises a cooling plate, a first battery cell, and a secondbattery cell, as shown in FIG. 1 . In some embodiments, multiple batterycells are coupled to each side of the cooling plate, as described abovewith regard to FIGS. 3 and 4 . As shown in FIGS. 5 and 6 , the coolingplate of the battery system comprises an input port and an output port.At step 702, cooling fluid is supplied to the input port of the coolingplate. As discussed above, the cooling fluid may be supplied by acooling fluid source such as a heat exchanger or other device. At step704, heat is absorbed in the cooling fluid from the first ends of thebattery cells through the surfaces of the cooling plate, generatingheated cooling fluid. For example, the cooling fluid can absorb heat asit passes through channel 508 of FIG. 5 . At step 706, the heatedcooling fluid is discharged through the output port of the coolingplate. In some embodiments, the cooling fluid is discharged and returnsto the cooling fluid source. In some embodiments, the cooling fluid isdischarged and returned to a separate device. The method of FIG. 7 ,which uses a cooling plate to cool the ends of batteries, enables, forexample, tightly packed battery cells to be efficiently cooled.

FIG. 8 is a flowchart 800 of a method for manufacturing a battery systemto increase volumetric efficiency for cooling. At step 802, a coolingplate with a first side and a second opposite side is provided. Thecooling plate may comprise a generally rectangular shape, as shown inFIG. 5 , or it may be a different shape, such as round. As shown in FIG.5 , the cooling plate may comprise one or multiple channels for coolingfluid to pass through the plate. At step 804, a first battery cell and asecond battery cell are provided. Providing each component may includemanufacturing or assembling the component itself, or obtaining thecomponent from a supply of components. As shown in FIG. 1 , the firstbattery cell and second battery cell may each comprise a first end, asecond end, and a longitudinal axis passing through the first and secondends. The battery cells may have electrical connectors as shown in FIG.2 that allow the cells to be arranged in series and parallelconfigurations (e.g., as shown in FIG. 3 ). At step 806, the first endsof the first and second battery cells may be coupled to opposite sidesof the cooling plate. For example, the first end of the first batterycell may be coupled to the first side of the cooling plate, and thefirst end of the second battery cell may be coupled to the second sideof the cooling plate, where the first and second battery cells areoriented in opposite directions, as shown in FIG. 1 . The ends of thebattery cells may be coupled to the cooling plate using any suitablecoupling element such as an adhesive, a nonconductive shroud, or both.It should be understood that there may be any suitable number of batterycells coupled to the cooling plate. It should also be understood thatthe cooling plate and coupled battery cells can be included in a batterymodule to power a load (e.g., an electric vehicle).

The foregoing is merely illustrative of the principles of thisdisclosure and various modifications may be made by those skilled in theart without departing from the scope of this disclosure. The abovedescribed embodiments are presented for purposes of illustration and notof limitation. The present disclosure also can take many forms otherthan those explicitly described herein. Accordingly, it is emphasizedthat this disclosure is not limited to the explicitly disclosed methods,systems, and apparatuses, but is intended to include variations to andmodifications thereof, which are within the spirit of the followingclaims.

What is claimed is:
 1. A battery system comprising: a cooling platecomprising: a first surface and a second surface, the first surface andthe second surface being on opposite sides of the cooling plate; and aninput port and an output port; a plurality of first battery cells eachcomprising a first face adjacent to the first surface of the coolingplate at a first thermal interface; and a plurality of second batterycells each comprising a first face adjacent to the second surface of thecooling plate at a second thermal interface, wherein: the pluralities ofthe first and second battery cells are arranged within a housing; thecooling plate comprise a first rectangular region within the housing anda second region outside of the housing; the input port and the outputport are arranged on the first surface outside of the housing; and acooling channel of the cooling plate within the second region narrowstowards and is coupled to the input port or the output port.
 2. Thebattery system of claim 1, wherein: a second end of each first batterycell and each second battery cell comprises a center portion and a rimportion; the center portion corresponds to a first electrical terminal;and the rim portion corresponds to a second electrical terminal.
 3. Thebattery system of claim 1, wherein each first battery cell and eachsecond battery cell comprises a cylindrical shape.
 4. The battery systemof claim 1, wherein the cooling plate comprises a cooling fluid.
 5. Thebattery system of claim 4, wherein: the cooling fluid enters the coolingplate through the input port and exits the cooling plate through theoutput port; and the cooling fluid travels within the cooling plate inthe first rectangular region in a clockwise manner and acounter-clockwise manner.
 6. The battery system of claim 5, wherein: thecooling plate comprises a plurality of cooling channels through whichthe cooling fluid can pass through from the input port to the outputport.
 7. The battery system of claim 4, further comprising an additionalcooling plate configured to cool additional battery cells, wherein thecooling plate and the additional cooling plate are coupled in parallelto a source of the cooling fluid.
 8. The battery system of claim 1,wherein a first end of each first battery cell and each second batterycell comprises a negative face and wherein a second end of each firstbattery cell and each second battery cell comprises a positive face. 9.The battery system of claim 1, wherein each first battery cell comprisesa respective vent configured to release gas during a thermal event, andwherein each second battery cell comprises a respective vent configuredto release gas during a thermal event.
 10. The battery system of claim1, wherein the plurality of first battery cells are arranged in a firstplurality of rows, wherein each row of the first plurality of rows isoffset from an adjacent row, wherein the plurality of second batterycells are arranged in a second plurality of rows, and wherein each rowof the second plurality of rows is offset from an adjacent row.
 11. Thebattery system of claim 1, wherein the plurality of first battery cellsare electrically connected in parallel and wherein the plurality ofsecond battery cells are electrically connected in parallel.
 12. Thebattery system of claim 1, wherein: the plurality of first battery cellscomprises a first plurality of subgroups of first battery cells, whereinthe first battery cells in each of the first plurality of subgroups areconnected in parallel and wherein the first plurality of subgroups areelectrically connected in series; and the plurality of second batterycells comprises a second plurality of subgroups of second battery cells,wherein the second battery cells in each of the second plurality ofsubgroups are connected in parallel and wherein the second plurality ofsubgroups are electrically connected in series.
 13. The battery systemof claim 1, wherein: a longitudinal axis of each first battery cell isparallel to a longitudinal axis of each second battery cell; and thefirst face of each first battery is spaced apart from the first face ofeach second battery a distance less than 8 millimeters in a directionparallel to the longitudinal axes of the first and second battery cells.14. The battery system of claim 1, wherein each first battery cell andeach second battery cell comprises a thermal conductivity that isgreater in a longitudinal direction than in a direction perpendicular tothe longitudinal direction.
 15. The battery system of claim 1, wherein:the cooling channel is a first cooling channel coupled to the inputport; and a second cooling channel of the cooling plate within thesecond regions narrows towards and is coupled to the output port. 16.The battery system of claim 1, wherein the cooling plate comprises oneor more cooling channels formed from three layers.
 17. The batterysystem of claim 1, wherein the cooling channel within the second regioncomprises an angled side relative to a side of the first rectangularregion.
 18. A battery system comprising: a first cooling platecomprising a first port, a second port, a first surface, and a secondsurface arranged opposite to the first surface; a plurality of firstbattery cells arranged on the first surface; a plurality of secondbattery cells arranged on the second surface; a second cooling platecomprising a third port, a fourth port, a third surface, and a fourthsurface arranged opposite to the third surface, wherein the third andfourth ports are on the third surface; a plurality of third batterycells arranged on the third surface; a plurality of fourth battery cellsarranged on the fourth surface; and a cooling fluid source configured toprovide cooling fluid to the first port and the third port, andconfigured to receive cooling fluid from the second port and the fourthport, wherein: the pluralities of the first and second battery cells arearranged within a housing; the first cooling plate comprise a firstrectangular region within the housing and a second region outside of thehousing; the first port and the second port are arranged on the firstsurface outside of the housing; and a cooling channel of the firstcooling plate within the second region narrows towards and is coupled tothe first port or the second port.
 19. The battery system of claim 18,wherein the cooling fluid source comprises a heat exchanger.
 20. Thebattery system of claim 18, wherein: the plurality of first batterycells each comprises a first end, a second end, and a longitudinal axispassing through the first end and second end of each first battery cell,wherein the first end of each first battery cell comprises a first face,and wherein the first face of each first battery cell is adjacent to thefirst surface of the first cooling plate at a first thermal interface;and the plurality of second battery cells each comprises a first end, asecond end, and a longitudinal axis passing through the first end andsecond end of each second battery cell, wherein the first end of eachsecond battery cell comprises a first face, wherein the first face ofeach second battery cell is adjacent to the second surface of the firstcooling plate at a second thermal interface, wherein the plurality offirst battery cells are oriented in opposite directions from theplurality of second battery cells.
 21. The battery system of claim 20,wherein: the second end of each first battery cell and each secondbattery cell comprises a center portion and a rim portion; the centerportion corresponds to a first electrical terminal; and the rim portioncorresponds to a second electrical terminal.
 22. The battery system ofclaim 18, wherein each first battery cell, each second battery cell,each third battery cell, and each fourth battery cell comprises acylindrical shape.
 23. The battery system of claim 18, wherein theplurality of first, second, third, and fourth battery cells areelectrically connected to form a battery pack.